1. Field of the Invention
This invention relates to cooling of computing system environments, and more particularly to an apparatus and system that enables in situ cooling using a rear door heat exchanger, especially during maintenance operations.
2. Description of Background
The industry trend has been to continuously increase the number of electronic components inside computing systems in order to achieve increases in processor performance. The increase in the number of electronic components, however, does not change the footprint of the computer system. Given this limited footprint, a continuous increase in the number of heat generating components creates challenging heat dissipation issues. These issues if not dealt with adequately, can harm the structural and data integrity of the computer system, making the effect felt both at a system and module level.
Conventionally, electronic packages or nodes in large environments, along with their associated electronics, are packaged in removable drawer configurations stacked within a rack or frame like housing structure. Cooling of the packages and components, in such cases is achieved by providing air flow in parallel paths and usually in a front-to-back direction. Air flow is often impelled by one or more air moving devices such as fans or blowers. In some cases it may be possible to provide increased air flow as needed, such as for power processor units. This objective is achieved through the use of a more powerful air moving device or by increasing the rotational speed of an existing one.
In addition to individual system heat dissipation issues in large computer installations, or data centers that house large banks of computer racks in close proximity, the heat dissipation issue is exacerbated even more. In such installations not only will the room air conditioning be challenged but the cost can be prohibitive.
An even greater problem occurring in data centers is that of air recirculation. Recirculation problems occur when some fraction of the heated air exiting from one rack is subsequently drawn into the air inlet of the same rack or a different nearby rack. This recirculation flow is complex in nature, leading to increased rack inlet temperatures that have been unaccounted for during server thermal design. In some cases, this sudden and unaccounted for increase can affect system integrity by causing electrical shorts and result in other problems occurring due to components exceeding their allowable operating temperatures.
In response to this problem, International Business Machines Corporation introduced Cool Blue technology including the rear door heat exchanger concept partly embodied in U.S. Pat. No. 7,385,810. That patent provides for method and apparatus that facilitates the cooling of an electronics rack employing a heat exchange assembly mounted to an outlet door cover hingedly affixed to an air outlet side of the rack. The heat exchange assembly includes a support frame, an air-to-liquid heat exchanger, and first and second perforated planar surfaces covering first and second main sides, respectively, of the air-to-liquid heat exchanger. The heat exchanger is supported by the support frame and includes inlet and outlet plenums disposed adjacent to the edge of the outlet door cover hingedly mounted to the rack. Each plenum is in fluid communication with a respective connect coupling, and the heat exchanger further includes multiple horizontally-oriented heat exchange tube sections each having a serpentine cooling channel with an inlet and an outlet coupled to the inlet plenum and outlet plenum, respectively. Fins extend from the heat exchange tube sections. However, this approach poses challenges especially during computer installation and service calls. With Cool Blue technology now becoming more pervasive, the present invention introduces enhancements to allow for an improved servicing of a rack including a rear door heat exchanger.